Between 15,000 and 20,000 people in the 'Arelerland' (the area around Arlon, in the province of Luxembourg in Belgium), which borders the Grand Duchy, speak Luxembourgish as their mother tongue. In the 1960s, there were about 50,000 speakers of Luxembourgish in the area.
In addition, almost 14.5% of the population in this area (about 34,500 people) have a basic knowledge of Luxembourgish.
Following the Treaty of London of 19 April 1839, a series of municipalities in the province of Arlon which were part of the Grand Duchy were henceforth attached to the Kingdom of Belgium.
Although initially there was no threat to Luxembourgish (also called Luxembourgish Franconian), the situation changed considerably after the First World War. In the immediate post-war period, German was rejected for being the language of the enemy. The Belgian authorities accused speakers of Luxembourgish of using a German dialect.
The situation deteriorated during the Second World War, when Belgians suspected people in the Arlon area of being allied with the enemy.
Luxembourgish managed to survive nevertheless, and remained very much alive in the Arelerland until the early 1960s. It then became less important, as French was made compulsory at nursery school.
The remaining Luxembourgish-speaking community has since created a cultural association called 'Arelerland a Sprooch asbl', which has the task of promoting Luxembourgish language and culture in Arlon and the surrounding area.